Radio Basics

Choosing a radio is a pretty complex and subjective thing. In this article I will break down the different kinds of radios, discuss their strengths and weaknesses, and try to give you some places to start. In future installments, I will discuss the advanced features offered with more expensive radios, and why you might want to consider investing a little more or upgrading in the future.

A lot of us come to combat robotics having some other RC hobby experience and we might have radios that we can already use… but are they the right kind? First let’s look at broad topics… RC model radios have been made to use many different radio bands over the years… Most competitions will require that you use modern 2.4ghz radios… so older radios might not be a good option unless you are just looking to mess around, or your local club allows the use of older FM radios. Fortunately, you can get budget friendly systems now for $25-$50, and though these radios are often limited in functionality and range, they will definitely perform well enough so that you can compete with folks that have more expensive gear. Breaking our options down into 3 basic categories based on how you use them pistol grip, traditional 2 stick, and game controller style radios.  

Pistol grip radios were developed in the early 90’s initially for ground and water-based RC vehicles and are set up to work well for this. Initially they only had 2 channels, one for throttle (a trigger) and steering (a wheel)… designed to be used with the trigger being pulled for forward motion, pushed for reverse/brake… and the wheel would turn clockwise for right and counter for left… they eventually added one or more extra channels for accessories (lights, etc) but most of the other channels are controlled with 2 or 3 position switches. Modern pistol grip radios function the same way, but more advanced ones have lcd screens, can be set up to remember setting for multiple receivers, have control systems that can let you mix channels, vary the rates of control, and some have other types of switches for the other channels. Some advance radios can control up to 8 channel receivers. I will talk about channel mixing and rate adjustments in a later article as these can be very valuable features for a radio to have.  The advantage of this radio setup is that it is very easy to pick up and use, we use them for demonstration robots for this reason. They are also very easy to acquire and are the most inexpensive option for a beginner. On the other hand, since both hands are used to control steering and speed, it becomes awkward to use them on bots with active weapon systems (like spinners, hammers, or lifters) These radios can be purchased for around $20 for a simple 2 channel model, and can go up to a couple hundred dollars for a high end radio. You can get a nice quality 3 channel programmable radio like the one in the picture. for about $40.

Stick radios were the first to be developed for RC hobbyists and were most used for RC aircraft. Most have at least 4 channels, and some go beyond 20 channels. The radios generally have 2 sticks (gimbals) that can be moved up/down and left/right. Each of gimbal controls 2 channels. Most radios additionally have switches, sliders, and/or knobs to control other channels. Generally one up/down axis of motion is designated for “Throttle” and it is most often located on the left gimbal… while the other 3 channels self-center (are spring loaded to return to the middle when released) the throttle is configured to remain in the position it is moved to. Some radios allow you to change the function of the throttle gimbal to set it to automatically center instead.  Just like the pistol grip radios, more advanced stick radios have control systems that let you configure them for channel mixing, rate adjustment, and many other features. These radios are probably the most challenging to get used to using, but are much easier to control for systems that require 3 or more channels that need to be controlled and offer more precise control when you get use to using them. Most folks who compete in combat robotics these days use stick radios.  More advanced radios can be linked to a computer for programming, have micro-SD card slots for additional memory and bios upgrades, and have the ability to receive telemetry from the bot/model that includes things like motor temperature and even GPS coordinates… they also can have alarms to warn you about battery levels. This type of radio is common and has a price range starting at about $35 and the high-end ones can cost over $1000. Most high-end radios are optimized for RC aircraft usage and include high strength transmitters and antennas that you won’t need, and telemetry functionality that isn’t really useful unless you are competing in a heavier weight class. You can get a beginner level programmable 6 channel radio like the one in the picture for about $50. Many folks who compete with us use this radio.

Game controller (gamepad) radios are new to the hobby. Designed to feel like the type of controller that console gamers use (PS3, XBOX, etc.) They generally have 2 gimbals like the stick radios, 6-8 channels, and several buttons or knobs for other functions. Some of these radios can be programmed with the radio plugged into another device (a phone or computer), and others have an onboard screen. There are fewer options in this class of radio since they are new, and most start at around $150, but there are a few feature-limited options in the $50 price range. The advantage to this type of radio is that the layout may already be familiar to you if you play video games and I believe that there will be more options in this category in the future.

In my opinion, as of today, the best value-to-performance radio is still the traditional stick radio. You can get a budget friendly and still programmable radio for around $50 and a feature packed mid-ranged radio for about $100. Other types of radios may suit your needs better, but you trade features and/or options with the other configurations. We have a selection of radios linked on our radio resources page that you can compare to see which features you prefer.